The Wyvern and others
 

UAL T38 Phlyer and I got off on a slight tangent with the EF-111 thread ending up with the Wyvern.

http://cdn-www.airliners.net/aviatio.../6/0924623.jpg

BAD looking machine. But then the Brits also had the beast, the Gannett which was a twin-engine machine driving two props.

http://www.bharat-rakshak.com/IAF/Hi...i/Prithi13.jpg

Not to be outdone, Douglas was working on the turbo-prop Skyraider which became the SkyShark. I read something a while back that they are restoring one of the SkySharks to flight status. The airplane, the last of seven, was reportedly at Chino.

http://www.flightglobal.com/blogs/ai...sharklarge.jpg

Wyvern Differences
 

IIICorps:

This pic of the Wyvern here is different from the one in the EF thread-drift: the exhaust isn't under the left side of the cockpit. It appears to be the long horizontal slot on the left side of the engine....which seems odd, as it doesn't look like it has any high-temperature metal there to cope with the exhaust.

The Gannett: Looks like an SBD and a Hudson had a bastard love-child.

But then, I flew the OV-10, and a few of us said it looked like an A-10 and a helicopter had a love-child.

The Skyshark: I wonder why Douglas used that hideous canopy instead of the original bubble?

I know that two props obviously produce more thrust then one, but does the thrust generated by two in this configuration generate more then the sum of the thrust generated by each prop if they were on their own?

Usually Not
 

The total thrust is usually slightly less. This is due to aerodynamic interference between the two props.

The reasons for doing it are usually:

1. Reduces the diameter of the propellor. It takes a certain amount of blade surface area to absorb the power of an engine. As engines got very powerful, the choice was to add more blades, or more diameter to provide enough area. I've never seen more than 6 blades on an engine (C-130J). Most I've seen in the 1940s: five.

However, if the diameter gets too great, the tips of the blades may achieve supersonic speed at normal rpm. This is a huge loss of efficiency.

Also, in tail-draggers, if the diameter is too great, ground-clearance with the spinning prop becomes an issue when landing/taking-off.

2. P-factor/slip stream. Huge engines have lots of torque and a hideous amount of P-factor. By having contra-rotating propellors (counter-rotating would be like a P-38 or OV-10; contra-rotating is two props on one shaft), the torque and P-factor are neutralized.

That makes sense. Thanks for the answer. Do you know why they were developing the props when they had jets? Were they for ground support?

Piper PA-48 enforcer
 

I'll throw this in the mix even though it's not contra-rotating - I've heard the prop was taken from the A-1D with a heavily modified P-51D airframe and an Avco-Lycoming YT-55-L-9 turboprop of 2,445 hp. The Piper PA-48 Enforcer:


http://i533.photobucket.com/albums/e...-1234P-027.jpg

The Enforcer actually was almost a completely different airframe. I went down to Eglin AFB when it was doing testing and everyone knew it was a dead-end deal. The USAF was NOT going to go back to props and it was NOT going back to tailwheels even though the Enforcer did show long loiter times, good lifting power for ord.

Joe Baugher weighs in here on the Enforcer.

Piper Enforcer

From reading, it seems this picture is of a TF-1 which used a RR Eagle PISTON engine. ?? Until now I had never heard of the Eagle engine with due cause in that only 15 were made and they were all used in the Wyvern prototypes.

The Wyvern then was re-engineered to take the Armstrong Siddeley Python turboprop. (lesson for me)

Here is the Wyvern S4. The nose is markedly different. (note: the Brits have almost as arcane a designation series as the old US Navy ones)

http://cdn-www.airliners.net/aviatio.../7/1289703.jpg


One sortie in the OV-10 out of Hurlburt. In the back seat and I think I lost 50% of my hearing from that one sortie.

Don't know but is sure kills any vis aft. Again, Joe Baugher writing on a little known airplane.
Douglas XA2D-1 Skyshark

What I also have stumbled on is the Tupolev Tu-91 "Boot" of which there was only one. humbly submitted.. bulldog-butt UGLY.

http://img124.imageshack.us/img124/8...1bycheknr1.jpg

Performance and Runway Length
 

Early Jets were pretty anemic in performance, both total thrust, as well as fuel-consumption (very thirsty..the J-79 in the F-4 was considered a huge improvement in specific fuel consumption!!).

As an example, the US has perhaps close to 100 runways around the country (mostly in the midwest) in the 10-13,000 ft long category, that were runways for B-47s (3000 B-47s were built).

British Carriers had very short decks; shorter than comparable US ships. The early jets didn't have the capability of taking off from those short decks...they couldn't accelerate fast enough.

But, the new-found power source of a turboprop (which was about a 100% increase in horsepower, lower engine weight, and while burning more fuel than a piston, about one-fourth of the fuel consumption of the early jets) made for a very capable airplane from a short-decked carrier.

And generally, carriers are best-suited for ground attack: move a floating 'airport' near the place you need to fight, because there is no other airport available. So yes, I would say that the Wyvern was primarily suited for CAS (and substantiated by its combat record in Suez).

I saw the Enforcer fly out of Eglin in 1984 (I was going through a school at Hurlburt). It flew over me on downwind, and despite the turboprop, sounded a lot like a P-51 at cruise-power (at full-throttle, the Merlin has a characteristic sound and bark).

The history I have read on it said that Piper claimed it was an 'all-new airplane.' But, knowledgable sources say the fuselage was actually a P-51D that was cut and lengthened (the lengthening was supposedly about where the tail wheel was originally; about a foot or two). The main-gear were also modified stock P-51 units (not sure if that was the wheel, the strut, or both).

One airplane was lost in testing, but the others performed as advertised.

Ironically, there is now a move to make the AT-6B Texan II....which would have significantly less dash-speed, load capacity, or hardpoints.

And, I'm sure, will cost a lot more.

The biggest fault I had with the OV-10 I flew was its vulnerability because it was slow...we could barely hit 200 KIAS. It would dive to 350 (which was scary!!) But we used to call it the "Slow-V-10."

I think the Enforcer would do about 250-275, and could true-out near 300-325. It would be an excellent airplane in a low-threat war like Iraq or Afghanistan: tons of loiter time, the ability to carry lots of ordnance despite the density altitude, low IR signature, and low operating cost. The plan was to hang two GAU-8s (the A-10 gun) in pods from the wings and rip 'em up.

One of the airplanes is sitting in a lot at the Edwards museum, awaiting restoration.

Now I know where Toyota got the inspiration for the Scion-series. :rolleyes:

I dont understand these silly British words, but they sure sound cool. ;)